This invention relates generally to a manually actuated dispensing pump having a reciprocable plunger operated by a surrounding plunger head capable of being selectively locked, in one embodiment, in a fully depressed position, and capable of being selectively locked in another embodiment, in a fully raised position relative to the pump body, any leakage of product through the pump being positively prevented in both such plunger locked positions.
The aforementioned application discloses a finger operated liquid dispensing pump having a plunger head capable of being locked down, in one embodiment, in a fully depressed position relative to the pump body in non-use conditions of shipping and storage. An annular upstanding lip seal on the pump body bears tightly against the inner surface of the plunger head in this lockdown position for sealing the container vent opening against leakage from the pump. However, no provision is made for avoiding leakage of product through the container vent opening in an unlocked position during periods of use as when the pump is tipped from its upright position.
In another embodiment disclosed in the aforementioned related application, the plunger head is capable of being locked in a fully raised position relative to the pump body, and a vent chamber is established for venting the interior of the container to atmosphere via the container vent opening located in the pump body, this vent chamber being closed by a depending skirt on the pump plunger in the fully raised and locked position of the plunger head.
My prior U.S. Pat. No. 4,343,417 discloses a dispensing pump of the pressure accumulating type capable of being locked in a fully raised position of the plunger head relative to the pump body, a vent chamber of the aforementioned type being established and being closed by an annular depending skirt on the plunger in the fully raised and locked position of the plunger head. This U.S. Pat. No. 4,343,417 was copending with the aforementioned related application, and is an improvement of my earlier U.S. Pat. No. 4,050,613 relating to a manually actuated dispensing pump of the pressure accumulating type having an accumulation chamber in communication with the pump chamber to effect discharge opening as the plunger is moved relative to the plunger head.
Also, my copending application Ser. No. 121,223, filed Feb. 13, 1980, now U.S. Pat. No. 4,402,432 constitutes an improvement over my U.S. Pat. No. 4,050,613 in that a vent chamber for plunger actuated pumps, incapable of being locked in any position, is established and is opened and closed during plunger reciprocation by an annular skirt depending from the plunger.